On 3/1/2021 7:52 AM, Borislav Petkov wrote:

On Wed, Feb 17, 2021 at 02:27:12PM -0800, Yu-cheng Yu wrote:

[...]

quoted

  static inline pmd_t pmd_mkdirty(pmd_t pmd)
  {
-	return pmd_set_flags(pmd, _PAGE_DIRTY | _PAGE_SOFT_DIRTY);
+	pmdval_t dirty = _PAGE_DIRTY;
+
+	/* Avoid creating (HW)Dirty=1, Write=0 PMDs */
+	if (cpu_feature_enabled(X86_FEATURE_SHSTK) && !(pmd_flags(pmd) & _PAGE_RW))

						      !(pmd_write(pmd))

There is a problem of doing that: pmd_write() is defined after this 
function.  Maybe we can declare it first, or leave this as-is?

--
Yu-cheng